1. Field of the Invention
The invention relates to vacuum cleaners.
2. Description of Prior Art
The invention relates more particularly to domestic vacuum cleaners used in offices and in the home. In simplest form the vacuum cleaners comprise an inlet mounted inside a sweeping head and an outlet, or exhaust, connected by a passage. An electrically driven fan is mounted in the passage to draw air through the passage to create a "vacuum" inside the head so that dirt (dust and debris) is drawn into the inlet in use. A filter is mounted between the inlet and the fan to collect the dirt which is retained in a dirt collection chamber for later disposal, as required. The electric motor provided to drive the tan can be powered by an alternating current (AC) or direct current (DC) supply. Normally either an AC or a DC supply is used. AC supply is converted in the vacuum cleaner to a DC supply. It is also possible to use a combined motor that can be operated by both an AC and a DC supply. If an AC to DC convertor or a combined motor is used, the cost and/or bulk (or weight) is significantly increased. This latter problem is especially a concern for hand-holdable vacuum cleaners.